Transconductance amplifier

The invention discloses a transconductance amplifier which comprises a first-stage amplifying circuit A1, a second-stage amplifying circuit A2, an error amplifying circuit EA and a negative transconductance circuit FB. The first-stage amplifying circuit A1 is used for amplifying an input signal. The second-stage amplifying circuit A2 is used for buffering an output signal of the first-stage amplifying circuit A1; the error amplifying circuit EA is used for adjusting the first-stage amplifying circuit A1; and the negative transconductance circuit FB is used for suppressing the differential error of the first-stage amplifying circuit A1 in a negative feedback mode. In the amplifier, the negative transconductance circuit FB counteracts the differential error generated by the first-stage amplifying circuit A1 through negative feedback, so that the noise and offset voltage caused by the differential error of the first-stage amplifying circuit A1 are suppressed, the noise and the offset voltage in an input signal a